[R] Two additive effets in random of lme

[Douglas Bates]

Papy Gaston wrote:

> how I can put two additive effects in random of lme ?

It is best to use the version of lme from the lme4 package to do this.

In that version you can use a formula for random like

   random = ~ 1 | rows + columns

The most general form of the random specification is as a named list 
where the names correspond to the grouping factors.

   random = list(rows = ~ time, columns = ~ 1)

This only works in the version of lme from the lme4 package.  It does 
not work in the version from the nlme package.